Currently known infrared sensors which are used to detect infrared radiation coming from fires operate in the 1 to 2.5 micron wavelength. Although such sensors are capable of detecting infrared radiation generated by a fire, they are subject to false alarm conditions due to the variation of reflected solar radiation reflected off the ground or off vegetation in the area of detection of the sensor. If, however, the sensitivity of the infrared sensor is extended beyond to the 4 or 5 micron wavelength, the ratio between the infrared radiation from the fire and infrared radiation coming from fluctuations of the ambient background temperature diminishes, making accurate detection of the fire less probable.
It would therefore be greatly advantageous to have an infrared fire detector which is optimized for detecting fires against an ambient background temperature with reduced succeptability to false alarms due to the variation of solar radiation from reflected sources.